The proposed research plans to accelerate the development of instrumentation for high field solid-state NMR studies of proteins. Probes optimized for oriented membrane samples will be designed and constructed at the Resource for Solid-state NMR of Proteins at the University of Pennsylvania for use with the very high field magnets at the National High Magnetic Field Laboratory at Florida State University. The highest field magnet currently available for solid-state NMR experiments at the University of Pennsylvania corresponds to a 1H resonance frequency of 700 MHz, which will be up-graded to a magnet operating at 900 MHz as part of the development plan, while the magnets available at Florida State University operate at fields corresponding to 840 - 1100 MHz. Significant engineering and testing of both electronic and mechanical components are necessary because of the trade-offs inherent in building magnets at these high fields. This instrumentation will be developed and applied to the structure determination of membrane proteins. Vpu, an 81 residue membrane protein from HIV-1, will be the principal system investigated as part of the development of the instrumentation. This protein is of interest as a small membrane protein which can be expressed and labeled in bacteria and as a potential target for antiviral drugs aimed at its two biological functions.